An induction furnace employs electromagnetic energy to induce electrical currents to flow within a charge of metal or metal alloy. The electrical resistance of the metal produces heat as a natural consequence of the induced currents flowing in the metal. The combination of applied electrical power and frequency can be chosen to create sufficient heat within the metal to cause it to melt. The molten metal can then be poured into molds or otherwise used to produce a wide variety of metal products.
The basic elements of an induction furnace include an electro-magnetic induction coil, a vessel having a lining of refractory material, and a structure for supporting the induction coil and vessel. The induction coil comprises an electrical conductor of sufficient size and current capacity to produce the magnitude of magnetic flux necessary to induce large currents in the metal charge. The magnetic flux represents the lines of force of a magnetic field. The magnetic field emanates from the furnace and surrounds the adjacent work area occupied by operating personnel and equipment.
There is a need to reduce the magnetic fields produced by the operation of induction furnaces. Although the health consequence resulting from exposure to magnetic fields is unknown, it is deemed prudent to provide a design and method for magnetic field reduction. However, it is well known that EMI (electromagnetic interference) can cause failure or destruction of electronic equipment resulting from exposure to high energy magnetic fields. Therefore, there is a need to protect operating personnel and equipment from magnetic field exposure caused by the operation of an induction furnace.